During the late 1990s it could be said that there were maybe just a few too many shooters hitting the scene and after a strong year in '99 for action/multiplayer shooters, 2000 came with a dry spell as far as blockbusters were concerned.

The Operative: No One Lives Forever (NOLF) gave the genre a much needed breathe of life. The game was presented with an Austin Powers meets James Bond feel, that provided an amusing dialogue and story.

To fulfill the spy role the main character in NOLF was armed with a supply of fitting gadgets, which you could use to stealth through the levels, though as an equally viable route you were welcome to run-n-gun your way through.

DreamWorks Interactive

Clive Barker's Undying (2001)

Despite the fact it was well received critically, Undying suffered from relatively poor sales and no multiplayer support to boot. This game approached the first person shooter genre in a way that can only be described as edgy and interesting nonetheless.

Undying is definitely one of the first person shooters you shouldn't have, but probably did miss.

Croteam

Serious Sam: The First Encounter (2001)

Sam may be serious, but Serious Sam: The First Encounter is as far from it as possible. The game resorted to ridiculously unrealistic action packed encounters that could lead to kill counts totaling over one thousand.

Relatively unique to this title at the time, you made nearly equal use of every weapon in your arsenal depending on your opponent and what the general situation called for instead of rolling through your opponents with the same favored weapon of destruction level after level.

While in some games, resorting to sheer madness play-style is something that you'd fall back on if your initial attempt failed, in Serious Sam it's fully supported and even encouraged which provides a blast of a time.

Serious Sam today: After the first encounter came the second, and then a true sequel in Serious Sam II (2005). A third game has been confirmed to be in the works but no release date has been set.